Field of the Invention
The invention relates to a rotor winding for an electrical machine, having a rotor axis and a multiplicity of electrically conductive turns stacked radially relative to the rotation axis and forming a plurality of axial sections as well as a plurality of tangential sections, each axial section formed approximately straight, aligned approximately parallel to the rotation axis and having associated first cooling channels aligned meridionally relative to the rotation axis and passing through all of the turns, and each tangential section bent about the rotation axis, connecting two axial sections to one another and having associated second cooling channels.
Such a rotor winding is based on European Patent 0 160 887 B1, German Patent DE 37 00 508 C2, German Published, Prosecuted Patent Application DE-AS 10 11 048 and an article from "Electrical Times", dated Mar. 10, 1966, page 354.
A "meridional" direction with respect to an axis is a direction which lies on a plane containing the axis. A direction is accordingly meridional if it can be composed of a component which is radial with respect to the axis and of a component which is parallel to the axis. Such a use of the term "meridional" largely corresponds to the use in the field of gas turbines and in the field of geodesy.
References to the construction, the production and the use of a rotor winding, in particular a rotor winding which is intended for a dynamo-electrical machine such as a turbogenerator, are based on an article entitled "Lauferwicklungen fur Turbogeneratoren" [Rotor Windings for Turbogenerators] by D. Lambrecht, contained in a book by H. Sequenz entitled "Herstellung der Wicklungen elektrischer Maschinen" [Production of Windings for Electrical Machines], Springer Press, Vienna and New York 1973, pages 169-199. German Published, Non-Prosecuted Patent Application DE-OS 16 13 196, German Published, Prosecuted Patent Application DE-AS 10 36 370, Published European Patent Application 0 166 990 A1 and Published European Patent Application 0 250 980 A1 are also of interest. German Published, Prosecuted Patent Application DE-AS 11 46 186 relates to a turbogenerator having a rotor winding which uses direct conductor cooling. A tangential section is connected at right angles to an axial section. The tangential section is cooled indirectly, and the axial section is constructed as a hollow conductor, through which cooling fluid flows.
European Patent 0 160 887 B1, which was mentioned initially, discloses a rotor winding, some of the axial sections of which are located within a rotor body, namely within slots which are provided in the rotor body, and some of which are located outside the rotor body. At both axial ends of the rotor body, the respective parts of the axial sections which are located outside the rotor body, together with the tangential sections, form so-called end windings, in which a tangential section in each case connects two axial sections to one another, and which are disposed outside a respective shaft, that projects from the rotor body along the rotation axis. The entire rotor winding is cooled through the use of a cooling gas, in particular air or hydrogen. The cooling of the end windings of the rotor winding is of particular interest, and that cooling is carried out by the cooling gas passing through meandering cooling channels which are formed by the end windings themselves and fillers that rest against the end windings and in which corresponding slots are provided. Such a rotor winding has been found to be particularly successful in practical use and, in particular, has made it possible to operate a turbogenerator, which is equipped with a correspondingly equipped rotor winding, at a rating which is considerably higher than the capabilities of the prior art. Using such a rotor winding, it is possible to operate an air-cooled turbogenerator of an appropriate construction at a rating of up to 300 MVA. If hydrogen is used as the cooling gas, an even higher rating can be achieved, because of its better cooling characteristics.
The article from "Electrical Times", dated Mar. 10, 1966, page 354, describes a rotor of a dynamo-electrical machine having turns. Each turn is guided in a slot in the rotor in an axial section which is bent through 90.degree. outside the slot, and merges into a tangential section. The tangential section and at least one region of the axial section which extends deep into the slot are constructed as a hollow conductor structure and are thus cooled directly by a cooling fluid flowing through the turn. In a further region of the axial section, which is located within the slot, that axial section is cooled by cooling fluid flowing in the radial direction through turns which are located one above the other.
U.S. Pat. No. 4,543,503 describes a cooling air system for rotor windings of a dynamo-electrical machine. End windings of the rotor windings are cooled through a system of communicating cooling channels. Thus, due to a centrifugal effect of the winding rotor, a low pressure zone is generated, by which a pumping effect is produced. Cooling gas is conducted through the cooling system through the use of that pumping effect.